1. Field of the Invention
The present invention relates to the art of preparing polymers, and more particularly to processes and apparatus for producing polyphenols. The invention is of particular advantage in the case of producing conventional and novel polyphenols featuring characteristics which make them suitable for the manufacture of heat-resistant, chemically resistant, and radiation-resistant materials as well as antistatic materials for coating and other applications. Moreover, polyphenols may be useful as starting materials and curing agents in the synthesis of heat-resistant epoxy resins.
The problem of providing a straightforward and inexpensive process for commercial production of polyphenols is presently needed, even though polymerization of phenols by oxidative polycondensation is well known to those skilled in the pertinent art.
2. Description of the Prior Art
Known in the art is a process for preparing polyphenols by oxidative heteropolycondensation in the presence of a catalyst or catalysts selected from the group consisting of chloride of copper, chloride of iron, chloride of aluminum, and impurities (U.S. Pat. No. 3,678,006 and Soviet Inventor's Certificate No. 448,186).
The polymers obtained in the above process are useful for a wide range of applications but the manufacture thereof is not always profitable. This is due to the fact that the catalysts specified are effective in equimolar ratios or those well in excess of the latter as regards the monomer.
Here account must be taken of a high cost of the catalysts as well as of the fact that they can be used in the polycondensation process but once.
A process for preparing polyhydroquinone is also described in Soviet Inventor's Certificate No. 440,387. This process includes oxidative polycondensation of hydroquinone in an aqueous medium in the presence of oxidizers as well as separation of the end product. Hydrogen peroxide (perhydrol) has been disclosed as an oxidizer in this process.
To effectively oxidize the monomer, an amount of perhydrol in the reaction mixture is to be at least 2.3 mole per one mole of monomer. No doubt the process is advantageous in that the reaction of polycondensation results in the formation of water only, which is easily separated from the end product.
While this process is advantageous as hereinabove described, it still has some significant disadvantages. Thus, an intensive aggressivity of perhydrol requires that there be used a costly corrosion-proof processing equipment. Furthermore, the process described involves special care in view of an explosive nature of perhydrol. Finally, perhydrol, which is used in major amounts, is a relatively high-cost material for an oxidizer.